SS-31 peptide is one of the more forgiving compounds to keep in a lab. It is short, it has no cysteine or methionine to oxidise, and it does not clump the way long sticky peptides do. Even so, we hear from people every month whose results went sideways, and when we dig into it the cause is nearly always storage or handling, not the material.
So here are the eight rules we follow ourselves. They are not complicated. Most take no extra time once they are habit. A couple of them will feel fussy until the day they save an experiment.
Table of Contents
Table of Contents
Why SS-31 peptide comes as a powder in the first place
Every vial of SS-31 peptide we ship is lyophilized, which is the technical word for freeze-dried. The SS-31 peptide is dissolved, frozen, and then the ice is pulled off under vacuum without ever becoming liquid water again. What is left is a dry cake or a loose powder at the bottom of the vial.
The point of doing this is stability. Nearly everything that damages a peptide needs water to happen. Hydrolysis needs water. Bacterial growth needs water. Most oxidation runs faster in solution. Take the water away and the clock all but stops.
That is why a dry vial can cross an ocean in a padded envelope and arrive fine, while the same peptide in solution would need dry ice and a prayer. It is also why the first rule is what it is.
Rule 1: Keep SS-31 peptide dry until you need it
Do not reconstitute a vial because it has arrived and you feel like getting organised. Leave it sealed. Powder keeps for a long time. Solution keeps for days to weeks.
If your study runs for three months and uses one vial a week, twelve vials stay in the freezer untouched and one gets opened each Monday. It sounds too simple to be worth writing down. It is the single most common thing people get wrong.
Rule 2: Minus 20 for the long term, and pick the freezer carefully
For anything longer than a few weeks, store dry SS-31 peptide at minus 20 degrees Celsius. Minus 80 is fine too if you have the space, but it is not necessary for this compound.
The type of freezer matters more than most people expect. Household style frost-free freezers stay frost-free by warming up several times a day to melt the ice off the coils. Your samples go through that cycle with them. A manual defrost laboratory freezer holds a steadier temperature. If frost-free is all you have, put the vials in an insulated box at the back, away from the door, so they are buffered from the swings.
For short periods, a few days to a couple of weeks, a sealed dry vial in the fridge at 2 to 8 degrees is acceptable. Room temperature for the length of a delivery is also fine. What you want to avoid is months on a shelf.
Rule 3: Keep light and moisture out
The dimethyltyrosine residue in SS-31 peptide is the chemically active part of the molecule. It is also the part most likely to react if you give it the chance. Light and oxygen both help that along.
In practice this means keeping vials in their box or in an opaque container, and not leaving them on a sunny bench while you set up. It is not a compound that falls apart in ten minutes of daylight. But there is no reason to test that.
Moisture is the bigger risk. A freeze-dried powder is hygroscopic, which means it pulls water out of the air. Once a vial has been opened, it will never be as dry again. If you must store an opened vial of powder, cap it tightly, wrap the cap with film, and put it in a container with desiccant.
Rule 4: Warm the vial before you open it
This is the fussy one. Take a vial straight from minus 20, pop the cap, and the cold glass and cold powder will condense water out of the room air within seconds. You cannot see it happen. You have just added water to your dry peptide, and if you then put the vial back in the freezer, that water goes with it.
The fix costs nothing. Take the vial out, leave it sealed on the bench for twenty to thirty minutes until it reaches room temperature, then open it. If you are in a humid climate, give it a little longer or let it warm inside a desiccator.
We would guess that half of all reports of a peptide that went off in storage trace back to skipping this step.
Rule 5: Choose the solvent for the experiment, not from habit
SS-31 peptide dissolves easily in water. With three positive charges at neutral pH, it is about as water-soluble as peptides get. You do not need DMSO, you do not need acetic acid, and you do not need to sonicate it.
What you dissolve it in should depend on where it is going next.
- For cell culture, sterile water or a simple buffer such as PBS, then dilute into medium.
- For analytical work, HPLC-grade water, or water with a little acetonitrile if that suits your method.
- For isolated mitochondria, whatever respiration buffer the assay calls for.
Make a concentrated stock rather than dissolving straight to the final working concentration. A stock of a few milligrams per millilitre is easy to pipette accurately and can be diluted to anything you need. Very dilute peptide solutions lose material to the walls of the tube, and you will not know how much.
When you add the solvent, run it gently down the inside wall of the vial instead of squirting it onto the powder. Then swirl. Do not shake hard and do not vortex for a minute straight. This peptide is tough enough to take it, but it is a good habit for every peptide, and habits should not depend on remembering which compound is in your hand.
Rule 6: Aliquot on day one
Once SS-31 peptide is in solution, the enemy is the freeze-thaw cycle. Each time a solution freezes, ice crystals form and the SS-31 peptide gets concentrated into the shrinking pockets of liquid between them. Each time it thaws, the reverse happens. Do that five or six times and you can measure the loss.
The answer is to split the stock into single-use portions the day you make it. Work out how much you use in one session, pipette that amount into a row of small tubes, label them, and freeze them all. Each tube is thawed once, used, and whatever is left is thrown away.
A few practical notes from doing this more times than we can count:
- Use low-binding polypropylene tubes. Ordinary tubes work, but low-bind tubes lose less.
- Label before you fill. Cold wet tubes do not take ink.
- Write the concentration, the date and the lot number. Not just the name.
- Freeze the tubes quickly. A metal block that has been sitting in the freezer does the job.
It adds fifteen minutes on day one. It removes a variable from every experiment after that.
Rule 7: Respect the clock on solutions
How long does SS-31 peptide last in solution? The honest answer is that it depends on the solvent, the concentration, the temperature and how clean your technique was. The Certificate of Analysis that ships with your order gives a timeframe for the lot, and that is the figure to go by.
As general guidance, a sterile stock kept at 2 to 8 degrees is something to use in days to a couple of weeks, not months. Frozen aliquots last much longer. Anything left at room temperature overnight should be treated with suspicion.
Contamination is the other half of this. A peptide solution is food for bacteria. If your stock goes cloudy, or develops anything floating in it, bin it. Do not filter it and carry on. Sterile technique when you reconstitute, and sterile-filtered solvent, prevent most of this.
Rule 8: Write it down
When something goes wrong three months into a project, the first thing you will want to know is which lot was in use, when it was reconstituted, and how many times that tube had been thawed. If none of that is written anywhere, you are guessing.
Keep a simple log. Date received. Lot number. Date reconstituted. Solvent and concentration. Number of aliquots made. It can be a page taped inside the freezer door. Staple the COA to it.
This is also what makes a re-order straightforward. When you can tell us exactly which lot you had and how it behaved, we can tell you whether the same lot is still available.
What degraded SS-31 peptide looks like
Usually it looks like nothing. That is the problem. A solution that has lost a fifth of its activity looks the same as a fresh one.
There are a few visible signs worth knowing. Powder that has gone sticky, glassy or yellowish has picked up moisture. A solution that is cloudy or has particles is contaminated or has come out of solution. A vial whose cake has collapsed into a film on the glass may simply have been warmed in transit, which is harmless, or may have been wet, which is not. If you are not sure, send us a photo.
The reliable test is analytical. If you have access to an HPLC, run a sample and compare the trace to the one on the COA. New peaks, or a main peak that has shrunk, tell you what your eyes cannot. We explain how to read those traces in our piece on SS31 peptide purity testing.
How our SS-31 peptide is packed and shipped
Knowing how it left us helps you judge how it arrived.
Each vial is sealed under a crimped cap and labelled with the compound, grade, fill and lot number. Vials are packed to stop them knocking together and shipped with the Certificate of Analysis for the lot. Because the powder is dry, transit at ambient temperature is not a concern over normal delivery times.
When the box arrives, check three things before it goes in the freezer. The seal on each vial is intact. The lot number on the vials matches the COA. The count is right. If anything is off, photograph it and write to us through the contact page the same day.
Which vial size makes storage easiest
This is a question that should come up at ordering time and often does not.
Small vials, such as the 5 mg Standard Grade or the 10 mg High Purity, suit labs that use a little at a time. One vial, one batch of aliquots, no opened powder going back into storage.
Larger vials, such as the 50 mg Ultra-Pure or the 100 mg Bulk, are cheaper per milligram but only make sense if you will reconstitute and aliquot the whole thing in one go. Opening a 500 mg vial, weighing out a little and resealing it, week after week, is the worst way to store any peptide.
If you are unsure which pattern fits, tell us how much you use per week when you enquire and we will suggest a mix. There is more on choosing sizes in our SS31 buying guide.
Storage for the other peptides we carry
The same rules apply, with small differences. BPC-157 is also stable and water-soluble. TB-500 is longer and benefits even more from gentle handling and low-bind tubes. GHK-Cu is a copper complex and its solutions are blue, which surprises people the first time. Retatrutide carries a fatty acid chain and can be slower to dissolve, so give it time and do not shake it.
Dry at minus 20, warm before opening, aliquot on day one. That covers all five.
A day-one routine for a new box of SS-31 peptide
Rules are easier to follow as a sequence. Here is what we would do, in order, on the day a box of SS-31 peptide lands on the bench.
- Open the box and count the vials against the packing list.
- Compare the lot number on a vial with the lot number on the Certificate of Analysis.
- Check each seal. Set aside anything cracked or loose and photograph it.
- Write the arrival date and lot number in the freezer log.
- Put all but the vials you need this week straight into the minus 20, in their box, at the back.
- Leave the working vial sealed on the bench for half an hour.
- While it warms, label your aliquot tubes and get the solvent ready.
- Open the vial, add solvent down the wall, swirl until clear.
- Pipette the stock into the labelled tubes, cap, and freeze.
- Note the reconstitution date, solvent, concentration and number of tubes in the log.
That is forty-five minutes, most of it waiting. After that, every experiment starts from a fresh, single-use tube of SS-31 peptide at a known concentration, and you never have to think about it again.
When the freezer fails
It happens to every lab eventually. A compressor dies over a long weekend, or someone leaves a door ajar, and you come in to a puddle.
For dry, sealed SS-31 peptide, a freezer failure is rarely a disaster. The powder tolerates room temperature for days. Move the vials to a working freezer, make a note of roughly how long they were warm, and carry on. If the outside of the vials got wet from meltwater, dry them and check that the labels are still readable.
Frozen aliquots are a different matter. If they thawed and sat at room temperature for more than a few hours, we would discard them and make fresh ones from a new vial. It is not worth building weeks of work on a stock you are unsure about. If they thawed but stayed cold, in a freezer that had only drifted up to fridge temperature, they are probably usable for non-critical work, and you should run a check before relying on them.
Two cheap precautions make this much less painful. A temperature logger or alarm on the freezer. And spare sealed vials held back, so that losing your aliquots costs you an afternoon and not a month.
Moving SS-31 peptide between sites
Labs relocate, and people carry samples to collaborators. A few points.
Move it dry if you possibly can. Sealed vials of powder can travel in a padded box at ambient temperature with no special arrangements. That is how they reached you in the first place.
If you must move solutions, send them frozen on dry ice by a courier that handles it properly, and treat each tube as having used up its one thaw when it arrives.
Send the paperwork with the material. A copy of the certificate and a note of the lot number, the reconstitution date and the concentration should travel in the same box. A tube labelled only with a name and a date is close to useless to the person receiving it.
And do not carry research chemicals in hand luggage across a border on the assumption that nobody will ask. Use a courier and proper documents.
Does grade change how you store it?
No. Standard, High Purity, Ultra-Pure and Bulk are all the same molecule and all behave the same way in storage. What changes is how much it matters if you get it wrong. A slip with a pilot vial costs you a few dollars. A slip with the single lot of SS-31 peptide set aside for a year-long study costs a great deal more. Store everything as if it were the expensive one, and the habit will be there when it counts.
The one-line version for the freezer door
If you want something to tape up where people will see it, use this. Dry SS-31 peptide lives at minus 20. Let the SS-31 peptide vial warm before opening. Dissolve SS-31 peptide in water, aliquot at once, thaw each tube only once. Log the lot. Four lines cover nearly everything that goes wrong with SS-31 peptide in a shared lab, and new students will actually read four lines.
Questions we get about storing SS-31 peptide
My SS-31 peptide sat at room temperature for a week in customs. Is it ruined?
Almost certainly not, provided the vial stayed sealed. Dry SS-31 peptide is stable at ambient temperature for that kind of period. Put it in the freezer now and carry on.
Can I store reconstituted SS-31 peptide at minus 20?
Yes, as single-use aliquots. Do not freeze a whole stock and thaw it each time you need some.
Does the vial need to be under nitrogen or argon?
Not for routine work. If you are storing opened powder for a long time, flushing the vial with inert gas before recapping does no harm.
How much liquid should I add?
That depends on the stock concentration you want. Divide the milligrams in the vial by the millilitres you add. Check with your supplier whether the stated fill is net peptide or gross powder, because it changes the sum. Our article on elamipretide peptide chemistry explains why.
There is hardly any powder in my vial. Is it under-filled?
Five milligrams of freeze-dried peptide is a very small amount to look at, and it often sits as a thin film. That is normal. The fill is by weight, not by appearance.
To sum up
Keep it dry. Keep it cold. Keep it dark. Warm the vial before opening. Dissolve in water or simple buffer. Aliquot the same day. Use solutions promptly. Write everything down.
Do those eight things and SS-31 peptide will behave the same in month six as it did in week one. If you are setting up a new project and want to order, current sizes and prices are on the SS-31 peptide page. Our minimum is 50 units, we reply to most enquiries the same day, and every order ships with its COA. For background on the compound itself, see our essential facts about SS-31, and for more on how peptides are freeze-dried there is a good general overview on Wikipedia.